Patent Application
20160220219
The disclosure relates generally to the field of radiography and more particularly to methods and apparatus for automatically positioning the x-ray source and detector based on exam type and patient characteristics.
In-room radiography apparatus are used for acquiring numerous types of radiographic images, taken from various portions of patient anatomy, for patients of various sizes, ages, and conditions. In a typical room radiography environment, technicians routinely switch between any of more than 50 types of exams, reconfiguring the imaging apparatus for each patient. Some amount of equipment setup time is required for each exam, as the patients are positioned and as the placement of the x-ray source and receiver are adjusted appropriately for each patient and for each exam type.
In conventional practice, some amount of automated positioning or pre-positioning may be provided, so that the operator or technician is provided with a reasonable starting point for carrying out each type of exam that is needed. Setup for each type of exam is performed by a time-consuming process of manually positioning the x-ray source and detector in place for the exam and recording these positions. Then, when a specific exam is requested, equipment can be automatically moved into the programmed position according to operator or technician instructions. A number of variables need to be stored for conventional setup, with the values relative to an origin position in the x-ray room.
Using conventional setup and recording methods for equipment positioning, equipment setup and programming is site-specific. Even where two radiography sites may have the same room size and other common characteristics, there are typically slight differences in how equipment is positioned in each site. The reference origin (0,0,0 in Cartesian coordinates) is generally one corner of the room that houses the radiography equipment. Movement for any of the various apparatus in the room is referenced to the reference origin for subsequent positioning. The coordinates for each exam must be individually programmed at each site, since the referenced position lies outside the radiography apparatus itself.
Although conventional practices provide a solution that enables some level of automation for initial apparatus positioning, these existing techniques have proven to be relatively cumbersome and costly. The sequence needed for setup and recording positions for each exam is time-consuming and it can take several hours for a service engineer and operations staff to work through a listing of prospective exams and configure the equipment for each exam type and for imaging patients of various heights and builds. As noted earlier, there is no benefit gained from setup of earlier installations; each site must be individually set up and its results programmed. Moreover, existing setup practices fail to adapt to different height and overall physical make-up of the patient population. The programmed setup parameters can be a poor match for patients who are shorter or taller than average. Additional setup work is often required to further adjust apparatus positioning to suit patient size and position after the x-ray source and detector are moved to their original positions.
Thus, it can be appreciated that there is a need for an auto-positioning utility to assist setup and configuration of a radiography site.
It is an object of the present disclosure to advance the art of radiography. A related object of the present disclosure is to address the need for an auto-positioning utility that does not require setup procedures for every possible type of exam and that further adapts to patient height and size characteristics. An advantage offered by methods of the present disclosure is straightforward customization of a radiographic system for patient height based on the anatomy of a local or regional population.
These objects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved by the may occur or become apparent to those skilled in the art. The invention is defined by the appended claims.
According to one aspect of the disclosure, there is provided an auto-positioning apparatus for an x-ray imaging system, comprising:
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings.
The elements of the drawings are not necessarily to scale relative to each other.
The following is a detailed description of the preferred embodiments, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures.
Various relative terms such as “above,” “below,” “top,” “bottom,” “height,” “depth,” “width,” and “length,” etc. may be used in the present disclosure to facilitate description of various embodiments. The relative terms are defined with respect to a conventional orientation of a structure and do not necessarily represent an actual orientation of the structure in manufacture or use. The following detailed description is, therefore, not to be taken in a limiting sense.
Where they are used, the terms “first”, “second”, and so on, do not necessarily denote any ordinal or priority relation, but may be used for more clearly distinguishing one element or time interval from another.
As used herein, the term “energizable” relates to a device or set of components that perform an indicated function upon receiving power and, optionally, upon receiving an enabling signal. The opposite state of “energizable” is “disabled”.
The term “actuable” has its conventional meaning, relating to a device or component that is capable of effecting an action in response to a stimulus, such as in response to an electrical signal, for example.
The term “modality” is a term of art that refers to types of imaging. Modalities for an imaging system may be conventional x-ray, fluoroscopy, tomosynthesis, tomography, ultrasound, MMR, or other types of imaging. The term “subject” refers to the patient who is being imaged and, in optical terms, can be considered equivalent to the “object” of the corresponding imaging system.
In the context of the present disclosure, the term “coupled” is intended to indicate a mechanical or electrical association, connection, relation, or linking, between two or more components, such that the state of one component affects the spatial disposition of a component to which it is coupled. For mechanical coupling, two components need not be in direct contact, but can be linked through one or more intermediary components or fields.
It will be understood that when an element is referred to as being “connected,” or “coupled,” to another element, it can be directly connected, communicatively connected, or coupled to the other element or intervening elements or magnetic fields may be present. In contrast, when an element is referred to as being “directly connected,” or “directly coupled,” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between,” versus “directly between,” “adjacent,” versus “directly adjacent,” etc.).
The term “exemplary” indicates that the description is used as an example, rather than implying that it is an ideal.
The term “in signal communication” as used in the application means that two or more devices and/or components are capable of communicating with each other in at least one direction via signals that travel over a signal path. Signal communication may be wired or wireless. The signals may be communication, power, data, or energy signals which may communicate information, data, power, and/or energy from a first device and/or component to a second device and/or component along a signal path between the first device and/or component and second device and/or component. The signal paths may include physical, electrical, magnetic, electromagnetic, optical, wired, and/or wireless connections between the first device and/or component and second device and/or component. The signal paths may also include additional devices and/or components between the first device and/or component and second device and/or component.
The statistical term “patient population” relates to a set of a plurality of patients from which statistical information can be obtained. Patient population-related data, such as average patient height, can be calculated from the set or a subset of patients that have been examined at a site or can be obtained from information about the patients who are most likely to be served at a particular imaging site.
The term “exam type” is associated with a body part that is to be imaged.
The perspective view of
Transport apparatus 22 in
In conventional practice, the radiography apparatus 10 has an origin O that is established in an initial setup procedure and that is typically considered to be at one corner of the radiography room. Any setup position for the components of apparatus 10 may then be expressed and stored with reference to the origin O. By identifying the spatial coordinates of a component in a particular position in relation to origin O, computer processor 12 can identify the distance needed to move that component to another desired position which has its own identifying spatial coordinates. For each of numerous exam types, component positioning for each element of the system must be individually identified and electronically stored, requiring hours of laborious positioning, testing, and storage procedures.
It should be noted that sensor 48 can have various arrangements for providing information about bucky 14 motion, with different configurations available according to actuator 46 type, such as when actuator 46 is a stepper motor, since the stepper motor can inherently store an origin position and uses step actuations for controlled incremental movement relative to the origin position. Multiple sensors 48 can be used to detect absolute position or relative position and position changes. According to an embodiment of the present disclosure, a radiography apparatus 10 uses a pair of encoders for sensing bucky 14 position. An optical encoder monitors drive shaft motion of the actuator motor and provides relative motion information when the motor is actuated. Another sensor provides absolute position information, such as a potentiometer, Hall sensor, or magnetic sensor, for example. Absolute position information establishes a baseline reference after power loss or at other times when it is necessary or useful to establish or re-establish a “home” reference position. It can be appreciated that any of a number of encoder arrangements are possible and can be implemented by those skilled in the motion control sensing arts. Other encoders and sensors, for example, can be used to detect rotation angle.
As is clear from
Unlike conventional positioning methods, embodiments of the present disclosure use the position of the detector 16 as an origin for corresponding movement of x-ray source 20. This alternative method simplifies the process of installation setup for the x-ray system at a particular site and allows the use of electronically stored tabular information that relates to patient anatomy for providing auto-positioning.
Origin O′ can be referenced to the detector 16 because processor 12 of radiography apparatus 10 is able to track movement of detector 16 and source 20 relative to the actuators 26, 46 that are energized to move them and sensors 24, 48 that provide feedback to the processor that indicates spatial position or angle based on spatial coordinates using one or more of the reference axes.
In order to calibrate radiography apparatus 10 so that its various sensors 24, 48 and actuators 26, 46 have a common reference, a single positioning procedure may be all of the positional calibration setup that is needed as part of installation. The arrangement of
For a C-arm installation, the needed information is somewhat simpler and calibration for room dimensions may not be needed. Position information is readily obtainable from the imaging apparatus itself, such as height of the axis of rotation for source, which relates to patient height, and detector and distance separating source and detector (SID).
Once the reference position is properly entered and stored, movement relative to the reference position can then be automated so that a suitable repositioning of detector 16 and its associated bucky 14 and source 20 can be effected for each type of exam. Significantly, this repositioning can be adapted to the dimensions of the patient, as described in more detail subsequently. A small amount of additional positioning data may also be stored, including parameters related to the location of possible physical obstructions, position of bed 30, preferred tube head orientation, and other data to support arrangements of the imaging components, such as for imaging extremities, for example.
According to an embodiment of the present disclosure, it may be useful or necessary to store additional calibration settings. Factors that determine this include variables in the arrangement of components that are used at a particular site. For example, the bed 30 (
With the reference position established, processor 12 can then use tabular information to adjust the position settings or spatial coordinates for radiography apparatus 10 components. Two types of tabular information are of particular value: exam-related data and patient-related data.
In conventional workflow for radiography, the majority of images that are acquired are from a standard set of images for different exam types. Each of these standard exam types has a standard setup practice. By way of example, Table 1 lists a number of standard exam types for C-spine views and some of the parameters that are typically used for positioning for each exam type.
The type of information provided in Table 1 is typical of information available for standard practice with other exam types. Embodiments of the present disclosure take advantage of this standardized information so that, knowing the starting position of x-ray system components within the x-ray room and the size of the patient, it can be possible to determine the needed movements from the starting position to an imaging position of each component for automating the equipment setup for imaging.
The distribution of specific bones and organs of the human anatomy is known to be generally proportional to the height of the patient, with some further consideration for age, weight, sex, and other factors. Embodiments of the present disclosure take advantage of this proportionality and use patient data where available or use default statistical data from the patient population to more accurately estimate the needed movement or adjustment from a current position to an imaging position of x-ray apparatus components for automatic positioning.
By way of example, and not of limitation, Table 2 lists a number of features of the human frame and their height on an adult of average size. These exemplary values are based on averages for the US population.
For imaging of upper extremities such as hand, fingers, thumb, wrist, elbow, and forearm, table-top imaging is typically used, employing the arrangement of
Patient height and weight data vary geographically and culturally, so that a single standard set of default values for worldwide use would be impractical. By way of example, heights for different anatomical regions for a typical 70-inch tall adult are listed in Table 3, with weight norms given by example in Table 4. By way of example, average patient heights for various countries are listed in Table 5. Also by way of example, some exemplary standard SID values are shown in Table 6.
It should be noted that electronically stored values such as those listed in Tables 1-6 are exemplary and that a number of other values can be stored, including values added or edited at a specific site. For example, the Table or Table Top SID at a particular site may need to be adjusted based on ceiling height limitations. The Horizontal Wall Stand SID might need to be adjusted based on the relationship of wall stand height with ceiling distance. The distance between the patient bed 30 (
An embodiment of the present disclosure enables automatically initiated positioning of radiography apparatus 10 components using stored information about the exam type and stored information about patient height and build, and related data such as the data listed in Tables 1 through 5, with preferred SID information from Table 6. The schematic diagram of
According to an alternate embodiment of the present disclosure, statistical values such as average patient height data for a particular site are adjusted over time, based on frequency of manual adjustment and trends detected in the adjustment data. For example, where manual adjustment related to patient height is needed in an appreciable number of cases and where the manual adjustment is predominantly downward, the software executed by processor 12 (
Still referring to
The logic flow diagram of
It should be noted that patient data can include patient height, weight, age, and other information that relates to particular anatomical characteristics of the patient. Where patient data of this type is available, values for patient height can be used directly for auto-positioning computation as described herein. Where patient data is not available or is incomplete, inconsistent, or ambiguous, default statistical values can be used for the auto-positioning computation that follows.
Continuing with the sequence of
Particularly where patient data is not readily available, step S820 in
For this example, with the actual patient height unknown, the detector 16 height for a patient is adjusted from a default adult setting by a height factor, using the following calculation:
60 in.×(height factor)=41 in.
The value of 60 in. for C-Spine imaging is acquired from Table 2. The height factor is computed from statistical Table 3 values as the ratio of Preadolescent Height to Medium Adult height: 48 in./70 in.
This calculation thus sets the center of the detector 16 at 41 in. The 15-degree angle and long SID set the tube head height from the floor for X-ray source 20 accordingly:
41 in.−(SID×sin(15))=(41−18.63)in.=22.36 in.
It should be noted that adjustments to default height values can be made according to region, such as by adjusting values proportionately according to height values that are characteristic of a particular patient population. Table 3 values, for example, would be applicable to a region or other patient population.
For auto-positioning calculation, the Table 2 values, suitable where patient height is 70 inches, can be scaled proportionately when patient height is less than or greater than 70 inches. Thus, for a patient of 62 inch height, a scaling factor of (62/70) can be applied to positioning calculations. The scaling factor(s) can also vary depending on patient age, sex, weight, and other factors, such as arthritis or other condition. Data that is indicative of patient height and can be acquired by processor 12 thus includes any of the actual measured or stored patient height value, a statistical height value from a regional or global patient population, and patient age, sex, weight, and other factors, such as arthritis or other condition. Default values can be used when the patient data that is indicative of patient height is unavailable or scanty. For example, if the only patient data that can be acquired indicates the sex of the patient, then the height used from stored statistical data for an adult of that sex would be used.
Referring back to
An image acquisition step S850 completes the imaging sequence in
Although embodiments of the present disclosure show an exemplary system that employs a ceiling mount, other equipment mounting arrangements are possible and are compatible with an embodiment of the present disclosure. Thus, for example, the x-ray source can be mounted to a pivoting arm or other device, rotatable about a number of axes. The x-ray source can be mounted as part of a floor-mounted system or a C-arm or U-arm system, for example. For a C-arm or U-arm system, the x-ray source and detector can maintain fixed positions relative to each other and only a single transport apparatus is needed.
Particular auto-position movements can be constrained following initial auto-positioning, depending on whether or not re-positioning established that different values should be applied. For example, if operator adjustment moves the x-ray source to a lower height, indicating a shorter patient, subsequent moves may be prevented or may use the lower height value. An error message can be displayed to the operator to indicate that an override of the calculated spatial position will be applied for subsequent images. Other rules restricting component movement may be applied, such as where the patient is in position and movement might be obstructed by or might inconvenience or endanger the patient.
For example, considering the C-Spine—LAO exposure example previously described, auto-positioning initially centered the detector at about 22.36 inch height. But if the 12 year-old patient is taller than average, subsequent manual adjustment is needed; the technician moves the x-ray source to a higher position, such as 25 inches for obtaining the C-spine LAO exposure. If the next image required in the exam for this patient is a C-Spine—RAO image, processor 12 (
Technician adjustments can also be stored for table-top and other exposures that do not use a bucky. Adjustments following auto-positioning can be saved by the system for subsequent images for a particular patient setup.
The same type of adjustment described with relation to height is also applied for settings wherein the detector and x-ray source are angled. Considering the tall 12-year old in the above example, where the detector is to be tilted, an alternate value for the height of the detector would be computed before the tilt is applied.
Tabular statistical data is used to establish various starting parameters for imaging, such as initial positions for imaging an average adult, for example. This data is stored as factory default data and can be modified by personnel at the x-ray site, such as to adjust for different populations where values such as average height and, optionally, weight and age may vary from factory default values. Practices such as preferred angles for incident radiation may also be modified at the site, to account for local preferences. Default view types for different exams can be modified, as well as values for SID, and preferred bucky positions.
Embodiments of the present invention may include machine computations based on spatial coordinates in one, two, or three dimensions. Those skilled in the art will recognize that these calculations may be performed by data processing hardware that is provided with instructions for image data processing. Because such image manipulation systems are well known, the present description is directed more particularly to programs, algorithms and systems that execute the method of the present invention. Other aspects of such algorithms and systems, and data processing hardware and/or software for producing and otherwise processing the image signals may be selected from such systems, algorithms, components and elements known in the art. Given the description as set forth in the following specification, software implementation lies within the ordinary skill of those versed in the programming arts.
The stored instructions of such a software program may be stored in a computer readable storage medium, which may comprise, for example: magnetic storage media such as a magnetic disk or magnetic tape; optical storage media such as an optical disc, optical tape, or machine readable bar code; solid state electronic storage devices such as random access memory (RAM), or read only memory (ROM); or any other physical device or medium employed to store a computer program. Using such software, the present invention can be utilized on a data processing hardware apparatus, such as a computer system or personal computer, or on an embedded system that employs a dedicated data processing component, such as a digital signal processing chip.
Consistent with one embodiment, the present invention utilizes a computer program with stored instructions that execute on computer processor 12 that is configured to (i) accept an instruction or data that indicates an exam type for the patient; (ii) acquire patient data that is indicative of patient height; (iii) determine the present position of the first transport apparatus and the intended imaging position according to the accepted instruction and acquired patient data; and (iv) provide a first positioning signal to move the first transport apparatus from its present position to the intended imaging position. Computer processor 12 may also be configured to process the image data that is stored from detector 16 and accessed from an electronic memory. As can be appreciated by those skilled in the image processing arts, a computer program of an embodiment of the present invention can be utilized by a suitable, general-purpose computer system, such as a personal computer or workstation that acts as a control processor or other type of data processing hardware. However, many other types of computer systems can be used to execute the computer program of the present invention, including an arrangement of networked processors, for example. The computer program for performing the method of the present invention may be stored in a computer readable storage medium. This medium may comprise, for example; magnetic storage media such as a magnetic disk such as a hard drive or removable device or magnetic tape; optical storage media such as an optical disc, optical tape, or machine readable optical encoding; solid state electronic storage devices such as random access memory (RAM), or read only memory (ROM); or any other physical device or medium employed to store a computer program. The computer program for performing the method of the present invention may also be stored on computer readable storage medium that is connected to the processor by way of the internet or other network or communication medium. Those skilled in the art will further readily recognize that the equivalent of such a computer program product may also be constructed in hardware.
It is noted that the term “memory”, equivalent to “processor-accessible memory” in the context of the present disclosure, can refer to any type of temporary or more enduring data storage workspace used for storing and operating upon stored data and accessible to a processor or computer system, including a database. The memory could be non-volatile, using, for example, a long-term storage medium such as electronic, magnetic, or optical storage. Alternately, the memory could be of a more volatile nature, using an electronic circuit, such as random-access memory (RAM) that is used as a temporary buffer or workspace by a microprocessor or other control logic processor device. Display data, for example, is typically stored in a temporary storage buffer that is directly associated with a display device and is periodically refreshed as needed in order to provide displayed data. This temporary storage buffer can also be considered to be a memory, as the term is used in the present disclosure. Memory is also used as the data workspace for executing and storing intermediate and final results of calculations and other processing. Computer-accessible memory can be volatile, non-volatile, or a hybrid combination of volatile and non-volatile types.
It is understood that the computer program product of the present invention may make use of various motion control and/or image manipulation algorithms and processes that are well known. It will be further understood that the computer program product embodiment of the present invention may embody algorithms and processes not specifically shown or described herein that are useful for implementation. Such algorithms and processes may include conventional utilities that are within the ordinary skill of the motion control and image acquisition and processing arts. Additional aspects of such algorithms and systems, and data processing hardware and/or software for producing and otherwise processing the images or co-operating with the computer program product of the present invention, are not specifically shown or described herein and may be selected from such algorithms, systems, hardware, components and elements known in the art.
The invention has been described in detail, and may have been described with particular reference to a suitable or presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.
